New research shows that limiting how pharmaceutical sales representatives can market their products to physicians changes their drug prescribing behaviors.

A team, led by the University of California, Los Angeles' Ian Larkin and Carnegie Mellon University's George Loewenstein, examined restrictions 19 academic medical centers (AMCs) in five U.S. states placed on pharmaceutical representatives' visits to doctors' offices. Published in the May 2 issue of the Journal of the American Medical Association, the results reveal that the restrictions caused physicians to switch from prescribing drugs that were more expensive and patent-protected to generic, significantly cheaper drugs.

Pharmaceutical sales representative visits to doctors, known as "detailing," is the most prominent form of pharmaceutical company marketing. Detailing often involves small gifts for physicians and their staff, such as meals. Pharmaceutical companies incur far greater expenditures on detailing visits than they do on direct-to-consumer marketing, or even on research and development of new drugs. Despite the prevalence of detailing and the numerous programs to regulate detailing, little was known about how practice-level detailing restrictions affect physician prescribing, until now.

For the study, which is the largest, most comprehensive investigation into the impact of detailing restrictions, the team compared changes in the prescribing behavior of thousands of doctors before and after their AMCs introduced policies restricting detailing with the prescribing behavior of a carefully matched control group of similar physicians practicing in the same geographic regions but not subject to detailing restrictions. In total, the study included 25,000 physicians and 262 drugs in eight major drug classes from statins to sleep aids to antidepressants, representing more than $60 billion in aggregate sales in the U.S.

"The study cannot definitively prove a causal link between policies that regulated detailing and changes in physician prescribing, but absent a randomized control, this evidence is as definitive as possible," said Larkin, assistant professor of strategy at UCLA's Anderson School of Management. "We investigated 19 different policy implementations that happened over a six-year period, included a control group of highly similar physicians not subject to detailing restrictions and looked at effects in eight large drug classes. The results were remarkable robust -- after the introduction of policies, about five to 10 percent of physician prescribing behavior changed."

Specifically, the researchers found that detailing policies were associated with an 8.7 percent decrease in the market share of the average detailed drug. Before policy implementation, the average drug had a 19.3 percent market share.

The findings also suggest that detailing may influence physicians in indirect ways.

"No medical center completely barred salesperson visits; salespeople could and did continue to visit physicians at all medical centers in the study," Larkin said. "The most common restriction put in place was a ban on meals and other small gifts. The fact that regulating gifts while still allowing sales calls still led to a switch to cheaper, generic drugs may suggest that gifts such as meals play an important role in influencing physicians. The correlation between meals and prescribing has been well established in the literature, but our study suggests this relationship may be causal in nature."

In light of these findings, the study indicates that physician practices and other governing bodies may need to take an active role in regulating conflicts of interest, rather than relying on individual physicians to monitor and regulate.

"Social science has long demonstrated that professionals, even well-meaning ones, are powerfully influenced by conflicts of interest," said Loewenstein, the Herbert A. Simon University Professor of Economics and Psychology at CMU. "A large body of research also shows that simply disclosing conflicts of interests is insufficient to reduce their influence, and may even exacerbate it. The results from this study underline the effectiveness of, and need for, centralized rules and regulations. We should not put the onus of dealing with conflicts on patients; the best policies are those that eliminate conflicts."

Larkin and Loewenstein also have a Viewpoint article in the same JAMA issue that calls for physicians to be compensated on a salary basis, instead of fee-for-service, to eliminate additional conflicts of interest.

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In addition to Larkin and Loewenstein, the research team included University of California, San Diego's Desmond Ang; Austrian Institute of Technology's Jonathan Steinhart; Williams College's Matthew Chao; Carnegie Mellon's Mark Patterson; Cornell University's Sunita Sah; New York University's Tina Wu; National Institute of Mental Health's Michael Schoenbaum; David Hutchins and Troyen Brennan from CVS Caremark.

The National Institute of Mental Health provided funding, and CVS Caremark provided data, for the study.

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